Temporary RWD

[Trip]

I know this is a daft question, and possibly i will be flamed at :twisted:

Removing the front drive shafts to convert the R to RWD would probably cook the centre diff. What about if you get a second(spare) diff and lock-weld and temporary fit it in the Gearbox so it will not cook its self ?

Or is there any other means to temporary put the car in RWD mode..

We do not have AWD dynos here in the whole country, and tuning the haltech on the road would be a bitch to get right.

To dyno tune cossie's they remove the transfer and install a piece from a RWD MT75 Gearbox.

 

[ChrisS]

Wouldnt it be easier to just unbolt the propshaft from the transfer box and run it temporarily as fwd?

 

[Trip]

It would still cook the diff

 

[vss irvine]

there must be some way of doing this, as ive heard of a few transfer boxes that have become faulty, giving drive only to the rear.
havent really looked into it, @ndrew on the modifiers runs a rwd gtir in nz, maybe worth contacting him? cheers

 

[Trip]

Cheers Martyn. I'll do a search

 

[Braveheart]

I'm interested in this too. I want to run safe power levels on a standard engine and box but can't beat evo or high powered scoobies in a 4WD class on the track.

 

[Trip]

^ so how will a RWD car help ?

 

[Ricky_GTi-R]

^ so how will a RWD car help ?

RWD and 4WD are different classes;-)

 

[GINGA]

This might interest you

Just spoke to my engine builder. The hesitating problem is solved, thank God 8) Yesterday evening he worked on it in his spare time to solve this issue. Seems that after the moving of the battery the Bosch fuel pumps began to work harder or something, since the overall fuelpressure had raised itself automatically, which resolted in a too rich fuelmap; he now turned this 0,5bar down (via de FPR) and everything is perfect again 8)
But he is a crazy man, in a nice way of speaking :lol: He has in his facility just a 2wd rollerbank, not a 4wd. And we wanted to do this fine tuning on the rollerbank. So what did he do??? He put the R on the front wheels on the rollerbank and lifted the rear :shock: Hence he made 7 runs :shock: :shock: 8) As said before the revlimiter is now set at 8200rpm. On the rollerbank the R gave only at 1,0bar boost 353hp on the wheels :shock: 8) Which is around 391hp on the cranck. This result is quite the same we had on the engine dyno. There it made at 7000rpm on 1,0bar allready 370hp. But while testing it seems that the wategate pipe bracket broke of. hmmmmm..... now we have to sort this issue again. But it keeps us from the streets :lol:

rgds
habib

Thanks guys for the nice comments 8)

Marc, well I can't do much about it , but the engine developed around 370-375hp@7000rpm at the cranck on 1,0bar when on the engine dyno. And eventually it developed around 530-550hp@around 7500-8000rpm at the cranck there around 2,0bar boost :shock:
As I said before my engine builder doesn't have a 4wd rollerbank, so he did it on the front wheels. The rear wheels were just in the air :shock: Thus it developed 353hp on the front wheels. And not at 7000 but at 8000 to 8200rpm. Probably when the car should be rolled on 4 wheels this will be lower. Now he calculated 11% drivetrain lost, so it came on 391hp on the engine, which is quite correct (with the engine dyno; so on the front wheels the lost is really around 11%). Should he rolled 4 wheels together (which he can't) maybe he should have calculated 25% drivetrain lost (which is quite common with 4 wd cars); but then the power on the wheels should be around 310hp I guess (to get 390 on the cranck with 25% lost).
The power dats's on the engine dyno are around 97-98% accurate, this is for sure. His roller bank is also quite reliable and has shown many times quite identical figures with the engine dyno.

We only use 98octane pump gas. The compression rate should be anywhere near 8,0:1; fuel pressure under boost is around 4,5bar with 1 bar and 5,5bar with around 2bar (on the engine dyno ). We rev the engine to 8200rpm. Note that the engine has quite angry cams with quite high lift. Also we use the DTA fully mapple ecu, and my engine builder has quite a few years experience with engine mapping. He has mapped the engine on the dyno for in total around 15hours :shock: Maybe these factors are responsible for the above mentioned power figures 8) I'm confident that your engine is strong and will develop good power figures

Thanks devilboy, we had the the loosened bolts fitted with loctite now Saturday we wondered why the engine started to move so much under acceleration; seems that the front-left engine mount has come loose alltogheter :shock: Really very interesting.....But the dammed clanking-clunking noise is still coming from the front-left side. Can't go there this saturday, so this we have to sort the week after that.... the sheet I forgotten to take with me so this I will get then to.

Rgds
habib

 

[stumo]

I don't think the center diff would last long doing that

 

[Trip]

Interesting read.

So the diff will not cook it self ?

 

[stumo]

trip, I would think it would

 

[Trip]

That’s what i thought actually. If there are no other repercussions, it wouldn't be that bad. I do have a spare centre diff.

 

[the chief]

but doesnt the centre diff put the power to the wheels that have the most resistance? (so if you had the rear lifted it would put all the power to the front?)

 

[Trip]

but doesnt the centre diff put the power to the wheels that have the most resistance? (so if you had the rear lifted it would put all the power to the front?)

correct, it removes the power from the slipping side and transfers it to the other side. when one side is in air, the diff would need to work harder transfering the load for a constant period of time which will eventually cook it. At least this is what i think happens.